[KPhotoAlbum] KIM File format compatibility

[Johannes Zarl-Zierl]

On Donnerstag, 18. Mai 2017 00:10:39 CEST Joe wrote:
> >> A proper fix needs to change the way we create export files. In the
> >> past, I was always hesitant to touch the .kim file format in order
> >> to avoid compatibility problems. Maybe it's time to revisit this
> >> decision...
> > 
> > I agree it needs to be backward compatible, so a newer kpa can import
> > an older .kim file.  I don't think the other direction is necessary;
> > if an old kpa can't import a new import file, you upgrade.
> 
> While I totally agree with this in principle, sometimes you can't
> upgrade because of dependencies.
> I had an install of something from a tarball fail today because of that.
> 
> The question then becomes: Are there any plausible scenarios where you
> would have a newer version the .kim file (which had to be generated on a
> newer version of KPA to start with) and still need to use it with an
> older version of KPA. I don't know the answer. E.g., Do all users have
> QT5 installed?

Qt5 is probably not the issue here. I see more of a point in users sticking to 
the stable version of some distro for one machine, but using another more 
bleeding-edge type of distro on another machine.


For changing the file format, I would propose action along the following line:
- Change the file extension (what about .kpx?)
- Add versioning to the file format, like we do have with the index.xml
- Disable new, incompatible options in the export dialog when a legacy .kim 
file is requested

Cheers,
  Johannes